1. Field of the Invention
The present invention relates to an image processing method, an image processing apparatus, and an image processing program for removing linear noise components from within images.
2. Description of the Related Art
Conventionally, radiation images are obtained by irradiating subjects with radiation, and detecting the amounts of radiation which have passed through the subject. The obtained radiation images are employed to perform diagnosis of the subjects. Different apparatuses are used to obtain these radiation images for each body part of the subjects. For example, mammography apparatuses are employed to obtain radiation images of subjects' breasts, and general imaging apparatuses are employed to obtain two dimensional radiation images, such as chest X rays.
There are cases in which linear noise (striped blurs) are generated in radiation images obtained by the aforementioned apparatuses. For example, in the case that image information accumulated in a radiation detector is read out using a line sensor, linear noise may occur in a sub direction (the vertical direction in a radiation image) due to differences in properties of each of the light receiving portions that constitute the line sensor. Alternatively, there are cases in which linear noise appears in a main direction (the horizontal direction in a radiation image) due to shock which is imparted to a line sensor.
There is a known method for removing the aforementioned linear noise by administering a filtering process onto radiation images, as disclosed in U.S. Patent Application Publication No. 20050053306. In this method, linear noise components are extracted from radiation image data, then the extracted linear noise components are subtracted from a radiation image which is represented by the radiation image data. In addition, the linear noise components are extracted after a preliminary process for reducing drastic changes in pixel values is administered.
The amount of time necessary to extract the linear noise components by the filtering method disclosed in U.S. Patent Application Publication No. 20050053306 depends on the image size of the radiation image and the size of the filter. A great number of calculations are necessary to extract linear noise components, which takes time. Therefore, there is a desire to shorten the time necessary for the linear noise component extracting process.